The etymology of hackish `foo' is obscure. When used in
connection with `bar' it is generally traced to the WWII-era Army
slang acronym FUBAR (`Fucked Up Beyond All Repair'), later
bowdlerized to foobar. (See also FUBAR.)

However, the use of the word `foo' itself has more complicated
antecedents, including a long history in comic strips and cartoons.
The old "Smokey Stover" comic strips by Bill Holman often
included the word `FOO', in particular on license plates of cars;
allegedly, `FOO' and `BAR' also occurred in Walt Kelly's
"Pogo" strips. In the 1938 cartoon "The Daffy Doc", a very
early version of Daffy Duck holds up a sign saying "SILENCE IS
FOO!"; oddly, this seems to refer to some approving or positive
affirmative use of foo. It has been suggested that this might be
related to the Chinese word `fu' (sometimes transliterated
`foo'), which can mean "happiness" when spoken with the proper
tone (the lion-dog guardians flanking the steps of many Chinese
restaurants are properly called "fu dogs").

Paul Dickson's excellent book "Words" (Dell, 1982, ISBN
0-440-52260-7) traces "Foo" to an unspecified British naval
magazine in 1946, quoting as follows: "Mr. Foo is a mysterious
Second World War product, gifted with bitter omniscience and
sarcasm."

Other sources confirm that `FOO' was a semi-legendary subject of
WWII British-army graffiti more-or-less equivalent to the American
Kilroy. Where British troops went, the graffito "FOO was here"
or something similar showed up. Several slang dictionaries aver
that FOO probably came from Forward Observation Officer. In this
connection, the later American military slang `foo fighters' is
interesting; at least as far back as the 1950s, radar operators
used it for the kind of mysterious or spurious trace that would
later be called a UFO (the older term resurfaced in popular
American usage in 1995 via the name of one of the better
grunge-rock bands).

Earlier versions of this entry suggested the possibility that
hacker usage actually sprang from "FOO, Lampoons and Parody",
the title of a comic book first issued in September 1958, a joint
project of Charles and Robert Crumb. Though Robert Crumb (then in
his mid-teens) later became one of the most important and
influential artists in underground comics, this venture was hardly
a success; indeed, the brothers later burned most of the existing
copies in disgust. The title FOO was featured in large letters on
the front cover. However, very few copies of this comic actually
circulated, and students of Crumb's `oeuvre' have established
that this title was a reference to the earlier Smokey Stover
comics.

An old-time member reports that in the 1959 "Dictionary of the
TMRC Language", compiled at TMRC, there was an entry that went
something like this:

FOO: The first syllable of the sacred chant phrase "FOO MANE
PADME HUM." Our first obligation is to keep the foo counters
turning.

For more about the legendary foo counters, see TMRC. Almost
the entire staff of what later became the MIT AI Lab was involved
with TMRC, and probably picked the word up there.

Very probably, hackish `foo' had no single origin and derives
through all these channels from Yiddish `feh' and/or English
`fooey'.